In 1998 Patel et al searched for Earth – Mars free – return trajectories that leave Earth, fly by Mars, and return to Earth without any deterministic maneuvers after Trans – Mars Injection. They found fast trajectory opportunities occurring two times every 15 years with a 1.4 – year duration, significantly less than most Mars free return trajectories, which take up to 3.5 years. This paper investigates these fast trajectories. It also determines the launch and life support feasibility of flying such a mission using hardware expected to be available in time for an optimized fast trajectory opportunity in January, 2018.
The authors optimized the original trajectory using patched – conic approximations ,and then modeled the trajectory using numerical integration with high fidelity force models and the JPL planetary ephemerides. We calculated an optimum trajectory launching in early January, 2018. At the Mars encounter, the spacecraft will pass within a few hundred kilometere of the surface. We investigated the Earth reentry conditions and developed some aerocapture options to mitigate G – loads on the returning crew. We also describe tradeoffs and studies necessary to develop the Thermal Protection System (TPS).
To size the Environmental Control and Life Support System (ECLSS) we set the initial mission assumption to two crew members for 500 days in a modified SpaceX Dragon class of vehicle. The journey is treated as a high – risk mission, which drives towards reliable — but minimalist — accommodations and provisions. As such, we investigated State Of the Art (SOA) technologies that would meet only basic human needs to support metabolic requirements and limited crew comfort allowances
One aspect is if there is a large solar mass ejection then the crew would likely be lost.